Methods and procedures for dynamic channel assignment and change in unmanned aircraft system (uas) control and non-payload communication

ABSTRACT

A dynamic channel assignment method includes receiving, at a ground control station (GCS), assignment of a first communication channel set from a spectrum authority before takeoff of the unmanned aircraft; receiving, at the GCS, assignment of a second communication channel set when the unmanned aircraft is to move from a first area using the first communication channel set to a second area using the second communication channel set due to a flight plan of the unmanned aircraft after takeoff of the unmanned aircraft; and after the unmanned aircraft enters the second area, maintaining, at the GCS, the first communication channel set when the unmanned aircraft reenters the first area due to the flight plan, and returning, at the GCS, the first communication channel set to the spectrum authority when the unmanned aircraft does not reenter the first area due to the flight plan.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the priority benefit of Korean PatentApplication No. 10-2016-0009969 filed on Jan. 27, 2016, in the KoreanIntellectual Property Office, the disclosure of which is incorporatedherein by reference for all purposes.

BACKGROUND

1. Field

One or more example embodiments relate to methods and procedures fordynamic channel assignment and change for controlling an unmannedaircraft, and more particularly, to methods and procedures fordynamically assigning and changing a communication channel in apoint-to-point (P2P) and point-to-multipoint (P2MP) unmanned aircraftcontrol communication system in order to efficiently use and manage alimited unmanned aircraft control spectrum in the national airspace.

2. Description of Related Art

All of constituent elements required for an entire flight process,including a control communication system, such as takeoff/cruise, flightcontrol, landing/retrieval, etc., together with an unmanned aircraft areexclusively referred to as an unmanned aircraft system (UAS) or aremotely piloted aircraft system (RPAS).

The UAS includes unmanned aircraft ground control equipment, an unmannedaircraft, and a data link. The data link refers to a wireless data linkbetween a ground radio station (GRS) and the unmanned aircraft, and maybe classified into a USA ground control and non-payload communication(CNPC) data link and a UAS payload data link.

A payload data link is a link used to transfer data associated withpayload, and is generally a wideband compared to a CNPC data link. TheCNPC data link is a link used to transfer data associated with unmannedaircraft flight control, UAS state monitoring, and CNPC link management,and includes a pilot/air traffic control (ATC) relay link and a UAScontrol link.

The pilot/ATC relay link is a communication link used to relay voice anddata between a pilot and an ATC through the unmanned aircraft, and theUAS control link is a link used to transfer control informationassociated with navigation safety between the pilot and the unmannedaircraft.

The UAS control link may be classified into a telecommand (TC) link anda telemetry (TM) link. The TC link is an uplink used to transfer flightorbit control information, all of unmanned aircraft system controlinformation required for safe flight, etc., from a pilot on the groundto the unmanned aircraft, and the TM link is a downlink used to transfera location, altitude, and speed of the unmanned aircraft, UAS systemoperation mode and state, navigation support data, tracking associatedwith detection and avoidance, a weather radar, video information, etc.,from the unmanned aircraft to the pilot on the ground.

A frequency for the unmanned aircraft ground CNPC data link generallyconsiders a C (5030 to 5091 MHz) band, which is distributed as a newexclusive band in WRC-12. In addition, a band distributed for anaeronautical mobile service may be considered, such as an L (960 to 1164MHz) band of which a standard is prepared to be available for anaeronautical mobile service in WRC-12.

In the C band, a frequency jamming effect with an existing system and amultipath delay spread are relatively small On the contrary, adirectional antenna needs to be used to secure a link margin and aDoppler effect of the C band is great by five times compared to that ofthe L band.

A low frequency band distributed for an aeronautical mobile service,such as the L band, has a relatively excellent propagationcharacteristic compared to the C band. The L band has a relatively lowpropagation loss of about 14 dB compared to the C band. However,existing navigation systems, such as distance measurement equipment(DME), automatic dependent surveillance-broadcast (ADS-B), a tacticalair Navigation system (TACAN), etc., are operated in the confusion.Thus, a frequency securement is difficult and a multipath delay spreadis great.

In general, the secured C band may be considered as a basic link ofground CNPC and the low frequency band, for example, the L band, anultra high frequency (UHF), etc., may be used to increase theavailability of the CNPC data link for navigation safety of the unmannedaircraft.

A connection type of the ground CNPC data link may include apoint-to-point (P2P) type and a network-based point-to-multipoint (P2MP)type.

In the P2P type, a single ground control station (GCS) directly forms adata link with the unmanned aircraft. The P2P type is generallyconsidered in an existing UAS.

In the network-based P2MP type, ground radio stations (GRSs) areconnected to a network and each GCS exchanges information with theunmanned aircraft through a ground network and a GRS.

The P2MP type capable of simultaneously forming a communication linkwith a plurality of unmanned aircrafts and also forming a nationalnetwork is to be considered as a next generation CNPC data link in orderto expand the application of public and private unmanned aircrafts.Technology associated with such a P2MP UAS CNPC system has not beenactively proposed.

Also, a CNPC channel is to be assigned to operate an existing P2P UASCNPC system. In an existing scheme, a spectrum authority staticallyassigns a channel during a relatively long time, for example, generally,1 year or more, when registering a UAS CNPC system. Thus, a channel thatis assigned to a specific UAS CNPC system may not be readily used atanother UAS CNPC system.

Accordingly, there is a need for technology for efficiently usingcommunication frequency resources for controlling an unmanned aircraftthat may efficiently operate a plurality of unmanned aircrafts in alimited frequency band exclusive for controlling an unmanned aircraft inorder to achieve the stable operation of the unmanned aircraft andexpand the demand for unmanned aircrafts.

SUMMARY

An aspect of at least one example embodiment is to provide a user with anew method and procedure for dynamically assigning and changing achannel in an unmanned aircraft system (UAS) control and non-payloadcommunication (CNPC) system that may be applicable to apoint-to-multipoint (P2MP) CNPC system capable of enhancing a use oflimited CNPC frequency and supporting a plurality of unmanned aircrafts.

Technical subjects to be achieved herein are not limited to theaforementioned subjects and one of ordinary skill in the art mayunderstand other technical subjects not described herein from thefollowing description.

According to an aspect, there is provided a dynamic channel assignmentmethod of a point-to-point (P2P) UAS including a spectrum authority, aground control station (GCS), a ground radio station (GRS), and anunmanned aircraft, the method including receiving, at the GCS,assignment of a first communication channel set for communicationbetween the GCS and the unmanned aircraft from the spectrum authoritybefore takeoff of the unmanned aircraft; receiving, at the GCS,assignment of a second communication channel set before the unmannedaircraft enters a second area when the unmanned aircraft is to move froma first area in which the first communication channel set is availableto the second area in which the second communication channel setdifferent from the first communication channel set is available due to aflight plan of the unmanned aircraft after takeoff of the unmannedaircraft; performing, at the GCS, communication with the unmannedaircraft using the second communication channel set when the unmannedaircraft enters the second area; and maintaining, at the GCS, the firstcommunication channel set when the unmanned aircraft reenters the firstarea from the second area due to the flight plan of the unmannedaircraft, and returning, at the GCS, the first communication channel setto the spectrum authority when the unmanned aircraft does not reenterthe first area due to the flight plan of the unmanned aircraft.

The dynamic channel assignment method may further include returning, atthe GCS, the first communication channel set to the spectrum authorityand receiving assignment of a third communication channel set availablein a third area from the spectrum authority when the unmanned aircraftenters the third area due to the flight plan of the unmanned aircraft.

The dynamic channel assignment method may further include monitoring, atthe GCS, a link state of a communication channel set in use; andchanging, at the GCS, the communication channel set by returning thecommunication channel set in use to the spectrum authority and byreceiving assignment of a new communication channel set when the linkstate of the communication channel set in use does not satisfy areference value.

The communication channel set may include a primary channel and a backupchannel, and the primary channel and the backup channel may be selectedfrom different frequency bands, respectively.

The changing of the communication channel set may include initiallychanging one of the primary channel and the backup channel included inthe communication channel set and subsequently changing a remaining onethereof.

The dynamic channel assignment method may further include providing, atthe GCS, information of a communication channel set assigned from thespectrum authority to the GRS; and verifying, at the GRS, whether thecommunication channel set is assigned from the spectrum authority, basedon information of the communication channel set.

The spectrum authority may further provide information indicating thatthe communication channel set is assigned from the spectrum authoritywhen assigning the communication channel set to the GCS, information ofthe communication channel set provided from the GCS to the GRS mayinclude information indicating that the communication channel set isassigned from the spectrum authority, and the GRS may verify whether thecommunication channel set is assigned from the spectrum authority basedon information indicating that the communication channel set is assignedfrom the spectrum authority.

According to another aspect, there is provided a dynamic channelassignment method of a P2MP UAS including a spectrum authority, a GCS, aGRS supporting a plurality of unmanned aircrafts, and an unmannedaircraft, the method including transmitting, at the GRS, information ofthe GRS to the spectrum authority, and receiving assignment of an uplinkfrequency set from the spectrum authority; registering, at the spectrumauthority, the uplink frequency set and information of the GRS to adatabase of the spectrum authority; receiving, at the GCS, assignment ofa first communication channel set for communication between the GCS andthe unmanned aircraft from the spectrum authority before takeoff of theunmanned aircraft; receiving, at the GCS, assignment of a secondcommunication channel set before the unmanned aircraft enters a secondarea when the unmanned aircraft is to move from a first area in whichthe first communication channel set is available to the second area inwhich the second communication channel set different from the firstcommunication channel set is available due to a flight plan of theunmanned aircraft after takeoff of the unmanned aircraft; performing, atthe GCS, communication with the unmanned aircraft using the secondcommunication channel set when the unmanned aircraft enters the secondarea; and maintaining, at the GCS, the first communication channel setwhen the unmanned aircraft reenters the first area from the second areadue to the flight plan of the unmanned aircraft, and returning, at theGCS, the first communication channel set to the spectrum authority whenthe unmanned aircraft does not reenter the first area due to the flightplan of the unmanned aircraft; and returning, at the GCS, the firstcommunication channel set to the spectrum authority and receivingassignment of a third communication channel set available in a thirdarea from the spectrum authority when the unmanned aircraft enters thethird area due to the flight plan of the unmanned aircraft.

The dynamic channel assignment method may further include monitoring, atthe GCS, a link state of a communication channel set in use; andchanging, at the GCS, the communication channel set by returning thecommunication channel set in use to the spectrum authority and byreceiving assignment of a new communication channel set when the linkstate of the communication channel set in use does not satisfy areference value.

The receiving the assignment of the communication channel set mayinclude receiving an approval of a GRS used at the GCS from the spectrumauthority, and receiving assignment of a time slot in an uplinkfrequency assigned to the GRS and a downlink frequency as thecommunication channel set, and the changing of the communication channelset may include changing, at the GCS, the downlink frequency of thecommunication channel set and the time slot of the uplink frequency.

The communication channel set may include a primary channel and a backupchannel, and the primary channel and the backup channel may be selectedfrom different frequency bands, respectively.

The changing of the communication channel set may include initiallychanging one of the primary channel and the backup channel included inthe communication channel set and subsequently changing a remaining onethereof.

The dynamic channel assignment method may further include providing, atthe GCS, information of a communication channel set assigned from thespectrum authority to the GRS; and verifying, at the GRS, whether thecommunication channel set is assigned from the spectrum authority, basedon information of the communication channel set.

The spectrum authority may further provide information indicating thatthe communication channel set is assigned from the spectrum authoritywhen assigning the communication channel set to the GCS, information ofthe communication channel set provided from the GCS to the GRS mayinclude information indicating that the communication channel set isassigned from the spectrum authority, and the GRS may verify whether thecommunication channel set is assigned from the spectrum authority basedon information indicating that the communication channel set is assignedfrom the spectrum authority.

According to another aspect, there is provided a distributed channelassignment method of a P2P UAS including a spectrum authority, a GCS, aGRS supporting a plurality of unmanned aircrafts, and an unmannedaircraft, the method including selecting, at the GCS, available channelsfor communication with the unmanned aircraft based on informationprovided from the spectrum authority; requesting, at the GCS, thespectrum authority for assigning a single channel among the availablechannels; verifying, at the spectrum authority, whether the requestedchannel is available in a flight area of the unmanned aircraft, anddetermining whether to approve the requested channel; and assigning, atthe spectrum authority, the requested channel to the GCS when therequested channel is determined to be approved.

The distributed channel assignment method may further include providing,at the spectrum authority, an assignment database and an interferenceanalysis algorithm for determining whether to assign the channel to theGCS, prior to selecting, at the GCS, the available channels. Theselecting may include analyzing, at the GCS, performing interferenceanalysis between frequency channels using the interference analysisalgorithm and selecting a communication channel compatible with anexisting communication channel present in a current flight area of theunmanned aircraft during flight of the unmanned aircraft.

The requesting may include providing, at the GCS, at least one ofcommunication link waveform information including a bandwidth of therequested channel, a maximum transmission power, and a receiversensitivity, a GRS to be used at the GCS, and a transceiver location andan antenna pattern of the unmanned aircraft.

The distributed channel assignment method may further include providing,at the GCS, communication channel link state information between the GCSand the unmanned aircraft to the spectrum authority; and updating, atthe spectrum authority, the interference analysis algorithm based on thecommunication channel link state information.

The distributed channel assignment method may further include notifying,at the spectrum authority, the GCS that the channel assignment isdisallowed if the channel assignment is impossible; receiving, at theGCS, the updated interference analysis algorithm from the spectrumauthority, reselecting an available channel using the updatedinterference analysis algorithm, and requesting again the spectrumauthority for the reselected available channel; and assigning, at thespectrum authority, the channel to the GCS when the requested channel isdetermined to be approved.

The requesting again the reselected available channel may includeproviding, at the GCS, at least one of the changed flight plan of theunmanned aircraft, communication link waveform information including abandwidth of the requested channel, a maximum transmission power, and areceiver sensitivity, a GRS to be used at the GCS, and a transceiverlocation and an antenna pattern of the unmanned aircraft in response toa change in the flight plane of the unmanned aircraft, the communicationlink waveform information, the GRS to be used at the GCS, and thetransceiver location and the antenna pattern of the unmanned aircraft.

According to some example embodiments, it is possible to provide a userwith a new method and procedure for dynamically assigning and changing achannel in a UAS CNPC system that may be applicable to a P2MP CNPCsystem capable of enhancing a use of limited CNPC frequency andsimultaneously supporting a plurality of unmanned aircrafts.

Additional aspects of example embodiments will be set forth in part inthe description which follows and, in part, will be apparent from thedescription, or may be learned by practice of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects, features, and advantages of the inventionwill become apparent and more readily appreciated from the followingdescription of example embodiments, taken in conjunction with theaccompanying drawings of which:

FIGS. 1A through 1C illustrate examples of a new channel assignmentprocedure after channel assignment and channel return in apoint-to-point (P2P) unmanned aircraft control and non-payloadcommunication (CNPC) system according to example embodiments;

FIG. 2 illustrates an example of a procedure of assigning and changing achannel in a P2P unmanned aircraft CNPC system according to exampleembodiments;

FIGS. 3A through 3C illustrate examples of a new channel assignmentprocedure after general assignment and channel return in apoint-to-multipoint (P2MP) unmanned aircraft CNPC system according toexample embodiments;

FIG. 4 illustrates an example of a procedure of assigning and changing achannel in a P2MP unmanned aircraft CNPC system according to exampleembodiments;

FIG. 5A illustrates an example of a distributed channel assignmentprocedure in a P2P type according to example embodiments;

FIG. 5B illustrates an example of a centralized channel assignmentprocedure in a P2P type according to example embodiments;

FIG. 6A illustrates an example of a distributed channel assignmentprocedure in a P2MP type according to example embodiments;

FIG. 6B illustrates an example of a centralized channel assignmentprocedure in a P2MP type according to example embodiments; and

FIG. 7 is a block diagram illustrating a computing system to execute adynamic channel assignment and change method and procedure forcontrolling an unmanned aircraft according to example embodiments.

DETAILED DESCRIPTION

Hereinafter, some example embodiments will be described in detail withreference to the accompanying drawings. Regarding the reference numeralsassigned to the elements in the drawings, it should be noted that thesame elements will be designated by the same reference numerals,wherever possible, even though they are shown in different drawings.Also, in the description of embodiments, detailed description ofwell-known related structures or functions will be omitted when it isdeemed that such description will cause ambiguous interpretation of thepresent disclosure.

Terms, such as first, second, A, B, (a), (b), and the like, may be usedherein to describe components. Each of these terminologies is not usedto define an essence, order or sequence of a corresponding component butused merely to distinguish the corresponding component from othercomponent(s). For example, a first component may be referred to as asecond component, and similarly the second component may also bereferred to as the first component. Unless otherwise defined, all terms,including technical and scientific terms, used herein have the samemeaning as commonly understood by one of ordinary skill in the art towhich this disclosure pertains. Terms, such as those defined in commonlyused dictionaries, are to be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art, andare not to be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

The example embodiments relate to methods and procedures in which aspectrum authority dynamically assigns and changes a channel to a nextgeneration uplink time division multiple access (TDMA)/downlinkfrequency division multiple access (FDMA) point-to-multipoint (P2MP)unmanned aircraft control communication system including a ground ratiostation (GRS) supporting a plurality of unmanned aircrafts as well as anexisting P2P unmanned aircraft control communication system based ondistributed and centralized channel assignment methods capable ofefficiently assigning and managing a limited unmanned aircraft controlspectrum through the spectrum authority. The proposed methods andprocedures may be applicable to other systems having a similar operationconcept as well as an unmanned aircraft control and non-payloadcommunication (CNPC) system.

Hereinafter, dynamic channel assignment methods and procedures between aspectrum authority and a UAS CNPC system including a ground controlstation (GCS) and P2P and P2MP GRSs.

A channel assignment procedure of the P2P unmanned aircraft CNPC systemwill be described with reference to FIGS. 1A through 1C.

FIGS. 1A through 1C illustrate examples of a new channel assignmentprocedure after channel assignment and channel return in a P2P unmannedaircraft CNPC system according to example embodiments.

FIG. 1A illustrates an example of assigning a single frequency channelset to the P2P unmanned aircraft CNPC system according to exampleembodiments.

Referring to FIG. 1A, in operation S111, a GCS requests a spectrumauthority for assigning a single CNPC channel set available in anairspace volume present in a flight path of an unmanned aircraft beforetakeoff.

In operation S122, in response to the request, the spectrum authorityassigns a frequency channel to the GCS based on a CNPC channel set unit.

Here, the frequency channel to be assigned may include a centerfrequency and a channel bandwidth, and the channel set may include aprimary channel or a backup channel

Whether to constitute the channel set using the primary channel or usingthe primary channel and the backup channel may be determined at the CCSbased on a channel support capability of the unmanned aircraft CNPCsystem, a current CNPC spectrum use state, and the like. If necessary,the spectrum authority may recommend a configuration of the channel setto the GCS.

That is, in operation A111, the GCS may request the spectrum authorityfor assigning a single primary channel or a single primary channel and asingle backup channel as a CNPC channel for operating the unmannedaircraft based on a flight plan, an unmanned aircraft/GRS capability, acurrent CNPC channel use state, and the like.

In operation S113, in response to the channel assignment, the GCStransmits, to the spectrum authority, a response that verifies thechannel assignment.

FIG. 1B illustrates an example of assigning an additional frequency setto the P2P unmanned aircraft CNPC system after assigning a frequency setaccording to example embodiments.

Operations S121 through S123 of FIG. 1B are the same as operations S111through S113 of FIG. 1A.

A CNPC channel set includes information about airspace volume in which acorresponding channel is available. When a flight plan to anotherairspace volume in which the assigned CNPC channel set is unavailable isincluded in a flight path of the unmanned aircraft, the flight to theother airspace volume is to be prepared.

Referring to FIG. 1B, in operation S124, the GCS requests the spectrumassignment for assigning another CNPC channel set available for theflight to the other airspace volume.

In operation S125, in response to the request, the spectrum assignmentassigns a frequency channel to the GCS based on a CNPC channel set unit.

In operation S126, in response to the channel assignment, the GCStransmits, to the spectrum assignment, a response that verifies thechannel assignment.

FIG. 1C illustrates an example in which the P2P unmanned aircraft CNPCsystem returns the assigned frequency set and receives assignment of anew frequency set according to example embodiments.

If three or more airspace volumes each in which a different CNPC channelset is available are present in the flight path of the unmannedaircraft, the GCS may use three CNPC channel sets in the flight path.

The GCS may continuously request the spectrum authority for assigning aCNPC channel set. However, since a CNPC spectrum is limited, a singleunmanned aircraft CNPC system may be limited to maintain maximum twoCNPC channel sets.

To secure another channel set in a state in which two CNPC channel setsare secured, the GCS needs to return one of the existing channel sets tothe spectrum authority and then request assignment of another channelset.

A backup frequency channel may be assigned simultaneously together witha primary frequency channel or may be assigned independently. That is,only the backup frequency channel between the primary frequency channeland the backup frequency channel may be changed.

For example, when the unmanned aircraft is flying in the second airspacevolume, the GCS may return an existing single channel used in the firstairspace volume and may request the spectrum authority for assigning aCNPC channel available in the third airspace volume.

Referring to FIG. 1C, in operation S131, the GCS notifies the spectrumauthority of a channel return schedule, and requests the spectrumauthority for assigning a new channel

That is, the GCS notifies the spectrum authority that the GCS is toreturn the existing single channel used in the first airspace volume,and requests the spectrum authority for assigning a CNPC channelavailable in the third airspace volume.

In operation S132, the spectrum authority notifies the GCS that the newchannel is assignable.

In operation S133, the GCS returns the maintained channel to thespectrum authority.

In operation S134, the spectrum authority verifies the channel returnand assigns the new channel to the GCS.

In operation S135, the GCS receives assignment of the new channel andtransmits, to the spectrum authority, a response that verifies thechannel assignment.

In the above procedure, if two or more frequency bands for CNPC arepresent, one of channels in one of the two or more frequency bands maybe selected as a primary frequency channel and one of channels inanother one thereof may be selected as a backup frequency channel.

A backup band is used to enhance the CNPC link availability, and abackup channel and a primary frequency channel are not selected from asingle CNPC band due to a nonlinearity issue of an amplifier of atransmitter for a GRS and an unmanned aircraft, and the like.

For example, in the case of C band and L band assigned for CNPC inWRC-12, a primary channel may be selected only from the C band by usingthe C band as a primary band and a backup channel may be selected onlyfrom the L band by using the L band as a backup band.

Also, in operations S131 through S135, when changing the primarychannel, the channel bandwidth as well as the center frequency may alsobe changed.

However, during the flight of the unmanned aircraft, change of thechannel frequency and the bandwidth is not recommended based on aservice rate required at the unmanned aircraft in real time. Thus, onlyin the case of requesting assignment of another primary channel so thatthe unmanned aircraft may move to the airspace volume in which theprimary frequency channel currently in use is unavailable, change of thefrequency band may also be requested.

In general, when requesting a bandwidth for the primary channel beforetakeoff, the bandwidth may be assigned based on a CNPC service to beused during the entire flight of the unmanned aircraft. Thus, whenchanging the primary channel, change of the channel bandwidth may not beconsidered generally.

However, when entering another airspace volume, a relatively greatbandwidth may be requested to be assigned. In this case, a relativelylarge amount of time may be used to receive channel assignment from thespectrum authority. Thus, a relatively small bandwidth may be requestedto be assigned based on only a required service. In this case, change ofthe bandwidth may also be considered in addition to change of thechannel frequency.

Two CNPC channel sets that a single unmanned aircraft CNPC system maysimultaneously maintain are for different airspace volumes that do notallow the same CNPC channel based on a frequency reuse policy.

Due to a limited CNPC spectrum, a single unmanned aircraft CNPC systemdoes not simultaneously maintain two CNPC channel sets each available ina single airspace volume.

Accordingly, change of the primary channel and the backup channel in aspecific airspace volume may proceed through a procedure of returning anexisting channel and receiving assignment of a new channel. In thiscase, the primary channel and the backup channel may not besimultaneously changed in order to prevent CNPC link outage betweenreturn of the existing channel and use of the new channel

Meanwhile, frequency change of the primary channel or the backup channelin the specific airspace volume is performed generally when a CNPCbackup link is in a poor state. When the link state is poor duringmonitoring the link state of the primary channel or the backup channel,for example, monitoring a bit error rate (BER), signal interference andnoise ratio (SINR), a link loss alert, and the like, it is possible torequest the spectrum authority for another primary or backup frequencychannel

As described above, a relatively small bandwidth may be requested to beassigned when changing the primary channel On the contrary, a bandwidthof the backup frequency channel may be differently changed depending onwhether a backup channel is a backup channel for enhancing the linkavailability by simultaneously transmitting and receiving the primarychannel and the backup channel, and a backup channel for enhancing thelink availability by switching to the backup channel in response toprimary channel link loss.

To simultaneously transmit and receive the primary channel and thebackup channel, the bandwidth of the primary channel is to be same asthat of the backup channel Accordingly, in the case of the backupchannel for enhancing the link availability by simultaneouslytransmitting and receiving the primary channel and the backup channel,once the bandwidth of the primary channel is changed, the bandwidth ofthe backup channel is to be changed regardless of a link state of thebackup channel

On the contrary, in the case of the backup channel for enhancing thelink availability by switching in response to the primary channel linkloss, the bandwidth of the backup channel may be changed separatelyregardless of the change of the bandwidth of the primary channel

However, the entire bandwidth of the L band for CNPC that is furtherlikely to be used as the backup channel is less than that of the C bandthat is further likely to be used as the primary channel Accordingly,when fixing the bandwidth of the backup channel to the bandwidthrequired to transmit only necessary information, for example, TC and TMinformation as in Data Class 1 of Baseline Radio of Radio TechnicalCommission for Aeronautics (RTCA) Minimum Operational PerformanceStandards (MOPS), in the emergency case regardless of the bandwidth ofthe primary channel, the bandwidth of the backup channel is not changedregardless of change of the bandwidth of the primary channel

FIG. 2 illustrates an example of a procedure of assigning and changing achannel in a P2P unmanned aircraft CNPC system according to exampleembodiments.

Referring to FIG. 2, in operation S201, a spectrum authority assigns afirst CNPC frequency channel set to a GCS before takeoff of an unmannedaircraft.

Here, the assigned frequency channel may be a distributed frequencychannel or a centralized frequency channel A description related theretowill be made below.

In operation S202, the GCS transfers channel assignment information toGRS1 for airspace volume 1. In operation S203, the GCS receives aresponse that verifies assignment information from the GRS1.

When the unmanned aircraft is required to enter airspace volume 2different from the airspace volume 1 due to the flight plan of theunmanned aircraft after takeoff of the unmanned aircraft in operationS204, the GCS receives assignment of a second CNPC frequency channel setin operation S205.

In operation S206, the GCS monitors a link state of the first CNPCfrequency channel

On the contrary, when the unmanned aircraft is not required to enter theairspace volume 2 different from the airspace volume 1 due to the flightplan of the unmanned aircraft after takeoff in operation S204, the GCSmay monitor the link state in operation S206 without receiving theassignment of the second CNPC frequency channel set.

In operation S206, the GCS may continuously monitor the link state ofthe primary channel and the backup channel while operating the unmannedaircraft CNPC system in the current airspace volume through the firstCNPC frequency channel set assigned before takeoff. Link statemonitoring may be performed by periodically monitoring a BER/FER, SINR,and the like.

In operations S207 and S211, the GCS determines whether it is difficultto use the first CNPC frequency channel set while monitoring the linkstate.

Whether it is difficult to use a CNPC frequency channel set may bedetermined based on whether the link state of the primary channel or thebackup channel satisfies a reference value.

When it is difficult to use the CNPC frequency channel set, the GCS mayreturn the channel to the spectrum authority and may receive assignmentof a new channel in operations S208 and S212.

To prevent a CNPC link outage, returning and assigning the primarychannel and backup channel set may be sequentially performed instead ofbeing performed simultaneously.

That is, when it is difficult to use all of the primary channel andbackup channel set, the

GCS may initially return the primary channel to the spectrum authorityand receive assignment of a new frequency channel in operation S208, maytransfer information about the newly assigned frequency channel to theGRS1 in operation S209, and may receive a response that verifies changeinformation from the GRS1 in operation S210.

The GCS may return the backup channel to the spectrum authority andreceive assignment of a new backup frequency channel in operation S212,may transfer information about the newly assigned backup frequencychannel to the GRS1 in operation S213, and may receive a response thatverifies change information from the GRS1 in operation S214.

Here, sequence of changing the primary channel and the backup channel isnot limited thereto. When the backup channel is initially changed, theprimary channel may be changed.

Also, when it is difficult to use either the primary channel or thebackup channel, only a corresponding channel may be changed.

When the unmanned aircraft enters an airspace volume different from acurrent airspace volume due to the flight plan of the unmanned aircraft,for example, when the unmanned aircraft is to enter airspace volume 2while flying in the airspace volume 1, the GCS changes the first CNPCfrequency channel set with the second CNPC frequency channel set inoperation S217.

The GCS may transfer assignment information of the second CNPC frequencychannel set to the GRS, for example, GRS2, for the different airspacevolume, for example, the airspace volume 2, before the unmanned aircraftenters the new airspace volume, in operation S215, and may receive aresponse that verifies the assignment information in operation S216.

When the unmanned aircraft enters the other airspace volume, the GCSoperates the CNPC system using the second CNPC frequency channel set inoperation S217.

Operations S215 through S217 may be applicable to an emergencysituation, for example, a case in which the CNPC system is to beoperated using the second CNPC frequency channel as well as a case inwhich the unmanned aircraft is to enter another airspace volume.

The GCS may determine whether to return the assigned first CNPCfrequency channel set, which may be determined based on whether theunmanned aircraft needs to reuse the first CNPC frequency channel byreentering the airspace volume 1 after flying the airspace volume 2.

When the unmanned aircraft reenters the airspace volume 1 immediatelyafter flying in the airspace volume 2 due to the flight plan of theunmanned aircraft in operation S218, the GCS does not return the firstCNPC frequency channel set.

However, when the unmanned aircraft enters airspace volume 3 instead ofreentering the airspace volume 1 immediately after flying the airspacevolume 2 due to the flight plan in operation S219, the GCS returns thefirst CNPC frequency channel set to the spectrum authority and receivesassignment of a third CNPC frequency channel set in operation S220.

Although not illustrated in FIG. 2, GRS3 for airspace volume 3 mayreceive assignment information of the third CNPC frequency channel setfrom the GCS and may set the CNPC system. Also, the GRS may transmit aresponse that verifies channel assignment and change informationincluding setting complete information.

To return the first CNPC frequency channel set, the GCS requests thespectrum authority for return of the first CNPC frequency channel set inoperation S221 a, and transfers return information of the first CNPCfrequency channel set to the GRS1 in operation S221 b. The GCS receivesa response that verifies return of the first CNPC frequency channel setfrom the spectrum authority in operation S222 a, and receives a responsethat verifies return information of the first CNPC frequency channel setfrom the GRS1 in operation S222 b.

In operation S221 b, the GCS is to notify the GRS1 having used thecorresponding channel of channel information assigned from the spectrumauthority and channel return information. In operation 222 b, the GRS1may close the CNPC system based on the channel return informationtransferred from the GCS and may transfer the response that verifies thereturn information.

The GCS may transfer channel information assigned from the spectrumauthority to the GRS3. Here, the GRS3 needs to verify whether thechannel information transferred from the GCS is channel assignmentinformation approved from the spectrum authority.

To this end, when the spectrum authority provides channel assignmentinformation to the GCS, the spectrum authority may transmit the channelassignment information to the GRS, and the GRS may verify whether theassigned channel is a valid channel by comparing information providedfrom the spectrum authority and information provided from the GCS.

However, in the above method, non-CNPC secured wired/wireless linkconnection between the GRS and the spectrum authority is to be forced.

As a method to outperform the above issue, when the spectrum authorityis to transmit channel assignment information to the GCS, the channelassignment information may also be transmitted by adding information,for example, a signature, indicating approval of the spectrum authorityto be recognizable only at the GRS and unverifiable at the GCS.

When providing channel assignment information to the GRS, the GCS mayalso provide information indicating that the channel assignment isapproved at the spectrum authority, and the GRS may verify that thechannel assignment information is valid information by verifying theinformation.

When the flight of the unmanned aircraft is terminated in the airspacevolume 2 without reentering the airspace volume 1 immediately afterflying in the airspace volume 2 due to the flight plan of the unmannedaircraft, the GCS may not return the first CNPC frequency channel set.

Also, when the unmanned aircraft is scheduled to enter the airspacevolume 3 before reentering the airspace volume 1 regardless of aschedule of reentering the airspace volume 1, the GCS may return thefirst CNPC frequency channel set and may receive assignment of a thirdCNPC frequency channel set to enter the airspace volume 3.

A CPNC frequency assignment and return may be performed because maximumtwo CNPC frequency channel sets are assignable to a single unmannedaircraft.

In addition to the above situation, the P2P unmanned aircraft CNPCsystem may need to change the GRS in the same airspace volume or mayneed to change the airspace volume in the same GRS.

When the GRS is to be changed in the same airspace volume, an existingCNPC channel set may be used and the GCS may change only the GRS withoutchanging a channel.

However, if the GRS is changed, CNPC characteristic information of achanged GRS may differ from that of a basic GRS due to a locationchange. Thus, an interference situation may vary and the existingchannel set may not be used.

In this case, the GCS needs to change a change by requesting thespectrum authority for a new channel set. Although the GCS does notchange the existing CNPC channel set since change by interference effectis absent, the GCS needs to provide changed GRS information to thespectrum authority by requesting the changed GRS information and theexisting CNPC channel set.

If the airspace volume is changed at the same GRS, the GCS may requestthe spectrum authority for a CNPC channel set and may provide GRSinformation, and the GRS may receive assignment of a new channel fromthe spectrum authority, as in an additional channel assignment procedurefor entering another airspace volume.

If a GCS for controlling the unmanned aircraft is transferred, thespectrum authority needs to be notified of related information so thatthe spectrum authority may monitor a GCS using a corresponding CNPCchannel

In the P2P unmanned aircraft CNPC system, the GCS receives assignment ofan uplink/downlink frequency channel (center frequency and channelbandwidth) from the spectrum authority.

In an uplink TDMA/downlink FDMA P2MP unmanned aircraft CNPC system, theGRS receives assignment of an uplink frequency channel (center frequencyand channel bandwidth) from the spectrum authority, and the GCS receivesassignment of a downlink frequency channel (center frequency and channelbandwidth) from the spectrum authority and an uplink time slot in theuplink frequency channel assigned to the GRS.

Accordingly, in the P2MP unmanned aircraft CNPC system, the GRSregisters CNPC transmission/reception device information (transceiverlocation, waveform, GRS location, antenna pattern, transmission power,receiver sensitivity, etc.) of the GRS to the spectrum authority and, atthe same time, receives assignment of the uplink frequency channel(center frequency and channel bandwidth) from the spectrum authority.

The GCS receives information about a GRS to be used due to the flightplan from the spectrum authority, receives assignment of an uplink timeslot in a frequency channel assigned to the GRS from the spectrumauthority, and receives assignment of a downlink frequency channel fromthe spectrum channel

The GCS receives assignment of a CNPC channel from the spectrumauthority based on a unit of a CNPC channel set (primary orprimary/backup uplink time slot/downlink frequency channel). That is,the GCS requests the spectrum authority for assigning a single primarychannel or a primary channel and a single backup channel as a CNPCchannel for operating the unmanned aircraft based on the flight plan,the unmanned aircraft/GRS capability, a current CNPC channel use state,and the like.

As described above, a single unmanned aircraft CNPC system may maintainthe maximum two CNPC channel sets. Thus, to secure another channel setin a state in which the two CNPC channel sets are secured, the unmannedaircraft CNPC system may return one of the existing channel sets and mayrequest assignment of another channel

The backup channel (uplink time slot and downlink frequency channel) maybe simultaneously assigned together with the primary channel (uplinktime slot and downlink frequency channel), or may be assignedindependently.

That is, only the backup frequency channel between the primary channeland the backup frequency channel may be changed.

Hereinafter, a channel assignment procedure of the P2MP unmannedaircraft CNPC system will be described with reference to FIGS. 3Athrough 3C.

FIGS. 3A through 3C illustrate examples of a new channel assignmentprocedure after general assignment and channel return in a P2MP unmannedaircraft CNPC system according to example embodiments.

FIG. 3A illustrates an example of assigning a single frequency channelset to the P2MP unmanned aircraft CNPC system according to exampleembodiments.

In operation S311, a GRS provides CNPC transmission/reception deviceinformation (transceiver location, waveform, GRS location, antennapattern, transmission power, receiver sensitivity, etc.) of the GRS to aspectrum authority and, at the same time, requests the spectrumauthority for assigning an uplink channel

In operation S312, the GRS receives assignment of an uplink frequencychannel (center frequency and channel bandwidth) from the spectrumauthority.

In operation S313, in response to the channel assignment, the GRStransmits a response that verifies the channel assignment to thespectrum authority.

In operation S314, the GCS requests the spectrum authority for assigninga single CNPC channel set available in the first airspace volume presentin a flight path of the unmanned aircraft.

In operation S315, in response to the request, the spectrum authorityassigns a frequency channel to the GCS based on a CNPC channel set unit.

Here, the frequency channel to be assigned may include a time slot in aGRS uplink frequency, and a downlink center frequency and channelbandwidth. The channel set may include a primary or primary/backupuplink time slot/downlink frequency channel.

That is, in operation S314, the GCS may request the spectrum authorityfor assigning a single primary channel or a single primary channel and asingle backup channel as a CNPC channel for operating the unmannedaircraft based on the flight plan, the unmanned aircraft/GRS capability,a current CNPC channel use state, etc.

In operation S316, the GCS may transmit a response that verifies thechannel assignment to the spectrum authority.

FIG. 3B illustrates an example of assigning an additional frequency setto the P2MP unmanned aircraft CNPC system after assigning a frequencyset according to example embodiments.

Operations S321 through S326 of FIG. 3B are the same as operations S311through S316 of FIG. 3A.

Here, in operations S321 through S323, in the P2MP unmanned aircraftCNPC system, the GRS receives assignment of the uplink frequency channel(center frequency and channel bandwidth). Thus, an additional GRS2 alsoprovides GRS CNPC transmission/reception information and receivesassignment of an uplink channel and provides a response that verifiesthe channel assignment.

A CNPC channel set includes information about an airspace volume inwhich a corresponding channel is available. When a flight plan toanother airspace volume in which the assigned CNPC channel set isunavailable is included in a flight path of the unmanned aircraft, theflight to the other airspace volume needs to be prepared.

In operation S327, after takeoff, the GCS requests the spectrumauthority for assigning another CNPC channel set for the flight to theother airspace volume.

In operation S328, in response to the request, the spectrum frequencyassigns a frequency channel based on a CNPC channel set unit.

In operation S329, in response to the channel assignment, the GCStransmits a response that verifies the channel assignment to thespectrum authority.

FIG. 3C illustrates an example in which the P2MP unmanned aircraft CNPCsystem returns the assigned frequency set and receives assignment of anew frequency set according to example embodiments.

If three or more airspace volumes each in which a different CNPC channelset is available are present in the flight path of the unmannedaircraft, the GCS requires three CNPC channel sets in the flight path.

The GCS may continuously request the spectrum authority for assigning aCNPC channel set. However, since a CNPC spectrum is limited, a singleunmanned aircraft CNPC system may be limited to maintain maximum twoCNPC channel sets.

Accordingly, to secure another channel set in a state in which the twoCNPC channel sets are secured, the GCS needs to return one of theexisting channel sets to the spectrum authority and then requestassignment of another channel.

For example, when the unmanned aircraft is flying in the second airspacevolume, the GCS may return an existing single channel used in the firstairspace volume and may request the spectrum authority for assigning aCNPC channel available in the third airspace volume.

Referring to FIG. 3C, in operation S331, the GCS notifies the spectrumauthority of a channel return schedule, and requests the spectrumauthority for assigning a new channel

That is, the GCS notifies the spectrum authority that the GCS is toreturn the existing single channel used in the first airspace volume,and requests the spectrum authority for assigning a CNPC channelavailable in the third airspace volume.

In operation S332, the spectrum authority notifies the GCS that the newchannel is assignable.

In operation S333, the GCS returns the maintained channel to thespectrum authority.

In operation S334, the spectrum authority verifies the channel returnand assigns the new channel to the GCS.

In operation S335, the GCS receives assignment of the new channel andtransmits, to the spectrum authority, a response that verifies thechannel assignment.

Also, in operations S331 through S335, when changing the primarychannel, the channel bandwidth as well as the center frequency may alsobe changed. In the case of uplink, the channel bandwidth/number of timeslots as well as the center frequency may be changed.

However, during the flight of the unmanned aircraft, change of thechannel frequency and the bandwidth is not recommended based on aservice rate required at the unmanned aircraft in real time. Thus, onlyin the case of requesting assignment of another primary channel so thatthe unmanned aircraft may move to the airspace volume in which theprimary frequency channel currently in use is unavailable, change of thedownlink frequency band and uplink time slot may also be requested.

In general, when requesting an uplink time slot and a downlink channelbandwidth for the primary channel before takeoff, the assignment may beperformed based on a CNPC service to be used during the entire flight ofthe unmanned aircraft. Thus, when changing the primary channel, changeof the uplink time slot and the downlink channel bandwidth may not beconsidered generally.

However, when entering another airspace volume, a bandwidth that isassigned from the spectrum authority to a GRS used for the unmannedaircraft CNPC system in the airspace volume may differ from a bandwidththat is assigned to the existing GRS. In this case, the uplink centerfrequency and the channel bandwidth need to be changed.

Also, according to an increase in a number of time slots and thebandwidth requested to be assigned, an amount of time used to receivechannel assignment from the spectrum assignment is highly likely toincrease. Accordingly, a relatively small downlink bandwidth and uplinktime slot may be requested to be assigned based on only a requiredservice. In this case, the channel change may be performed together withchange of the center frequency of the uplink/downlink channel based onchange in the downlink channel bandwidth and a number of uplink timeslots.

Two CNPC channel sets that a single unmanned aircraft CNPC system maysimultaneously maintain are for different airspace volumes that do notallow the same CNPC channel based on a frequency reuse policy.

Due to a limited CNPC spectrum, a single unmanned aircraft CNPC systemdoes not simultaneously maintain two CNPC channel sets each available ina single airspace volume. Accordingly, change of the primary channel andthe backup channel in a specific airspace volume may proceed through aprocedure of returning an existing channel and receiving assignment of anew channel. In this case, the primary channel and the backup channelmay not be simultaneously changed in order to prevent CNPC link outagebetween return of the existing channel and use of the new channel

Meanwhile, frequency change of the primary channel or the backup channelin the specific airspace volume is performed generally when a CNPCbackup link is in a poor state. When the link state is poor duringmonitoring the link state of the primary channel or the backup channel,for example, monitoring a BER, an SINR, a link loss alert, and the like,it is possible to request the spectrum authority for another primary orbackup frequency channel.

As described above, a relatively small bandwidth and a small number oftime slots may be requested to be assigned when changing the primarychannel On the contrary, a downlink frequency bandwidth and a number ofuplink time slots of the backup frequency channel may be differentlychanged based on whether a backup channel is a backup channel forenhancing the link availability by simultaneously transmitting andreceiving the primary channel and the backup channel, and a backupchannel for enhancing the link availability by switching to the backupchannel in response to primary channel link loss.

To simultaneously transmit and receive the primary channel and thebackup channel, the number of uplink time slots and the downlinkbandwidth of the primary channel are to be same as those of the backupchannel. Accordingly, in the case of the backup channel for enhancingthe link availability by simultaneously transmitting and receiving theprimary channel and the backup channel, once the number of uplink timeslots and the downlink bandwidth of the primary channel are changed, thenumber of uplink time slots and the downlink bandwidth of the backupchannel are to be changed regardless of a link state of the backupchannel On the contrary, in the case of the backup channel for enhancingthe link availability by switching in response to the primary channellink loss, the bandwidth of the backup channel may be changed separatelyregardless of the change of the bandwidth of the primary channel

However, the entire bandwidth of the L band for CNPC that is furtherlikely to be used as the backup channel is less than that of the C bandthat is further likely to be used as the primary channel Accordingly,when fixing the bandwidth of the backup channel to the bandwidthrequired to transmit only necessary information, for example, TC and TMinformation as in data class 1 of baseline radio of RTCA MOPS, in theemergency case regardless of the bandwidth of the primary channel, thebandwidth of the backup channel is not changed regardless of change ofthe bandwidth of the primary channel

As described above, in the P2MP type, a single GRS simultaneouslysupports a plurality of unmanned aircrafts. A connection scheme betweenthe single GRS and the plurality of unmanned aircrafts uses a TDMAscheme in the case of uplink and uses an FDMA scheme in the case ofdownlink.

Accordingly, in the case of uplink, the unmanned aircrafts supported atthe single GRS use the same frequency channel and may be identifiedbased on a time slot. Accordingly, the spectrum authority assigns anuplink frequency channel and an uplink time slot to each GCS. Thespectrum authority needs to be aware of a GRS to be used at the GCS andtime slot assignment information associated with the GRS.

In the case of a GRS, a further large number of time slots may berequired according to an increase in a number of unmanned aircraftssupported at the GRS. In this case, a CNPC channel frequency bandwidthis to be increased. However, it may not be easy for the GRS todynamically change the channel frequency bandwidth since the GRSsupports a plurality of unmanned aircrafts.

If the GRS dynamically changes the channel frequency bandwidth, the GRSneeds to notify an unmanned aircraft having formed a CNPC communicationlink with the GRS of the change and the GRS needs to dynamically changea receiver according to the change of the frequency bandwidth of theGRS.

Accordingly, an uplink frequency may be semi-statically assigned to theGRS in order to further efficiently manage a channel and to reduce P2MPcommunication complexity.

Also, in the case of dynamically changing the uplink frequency channelof the GRS, the GCS using the corresponding GRS needs to transferchannel information to the GRS every time the GCS requests the spectrumauthority for a channel. Thus, a network connection between the GRS andthe spectrum authority is required. Accordingly, an uplink frequency maybe semi-statically assigned to the GRS in order to further efficientlymanage a channel and to reduce P2MP communication complexity.

Since an uplink frequency is statically assigned to the GRS during apredetermined amount of time, a method in which a GRS operator assignsin advance an uplink frequency channel based on the GRS capability whileregistering the GRS and the spectrum authority assigns an uplink timeslot and a downlink channel in response to a channel request from theGCS may be employed.

Here, the spectrum authority may immediately transfer, to the GRS,information about a channel assigned to the GCS. Instead of transferringthe information to the GRS, the GCS may receive corresponding GRSinformation from the spectrum authority and may notify the GRS of thecorresponding information in response to attempt CNPC communicationthrough the GRS. However, as described above, when transferring channelassignment information to the GRS, an additional network between thespectrum authority and the GRS is required. Thus, channel informationmay be transferred from the GCS to the GRS, which is similar to the P2Ptype.

The uplink frequency bandwidth of the P2MP type may be relatively greatcompared to that of the P2P type. Thus, when a P2P CNPC channelassignment request and a P2MP CNPC channel assignment request coexist,channel assignment for the P2MP type having a relatively wideband may bedifficult. Accordingly, when performing frequency assignment withrespect to the P2P CNPC and the P2MP CNPC, the spectrum authority mayneed to separate a frequency to be assigned for the P2P type and afrequency to be assigned for the P2MP type based on the above aspect.

FIG. 4 illustrates an example of a procedure of assigning and changing achannel in a P2MP unmanned aircraft CNPC system according to exampleembodiments.

The channel assignment and change procedure of the P2MP type may besimilar to that of the P2P type, however, may differ in that an uplinkfrequency is assigned to a GRS before a request for channel assignmentfrom a GCS, P2MP GRS information is registered in advance to a spectrumauthority, a GRS to be used at the GCS is approved from the spectrumauthority, the spectrum authority assigns a time slot and a downlinkfrequency available in the GRS to the GCS, frequencies of a primarychannel and a backup channel in the same airspace volume are changedonly in downlink, and only a time slot is changed in uplink.

Operations S403 through S424 b of FIG. 4 may be matched to operationsS201 through S222 b of FIG. 2, and the channel assignment and changeprocedure of the P2MP type may further include operations S401 and S402.Also, a configuration of a frequency channel set assigned from thespectrum authority to the GCS differs, which will be described withreference to FIG. 4.

In operation S401, a GRS1 registers information of the GRS1 to thespectrum authority and receives assignment of an uplink frequency.

Operation S401 corresponds to operations S311 through S313 of FIG. 3A.The GRS provides CNPC transmission/reception device information(transceiver location, waveform, GRS location, antenna pattern,transmission power, receiver sensitivity, etc.) of the GRS to thespectrum authority and, at the same time, requests the spectrumassignment for assigning an uplink channel. The GRS receives assignmentof an uplink frequency channel (center frequency and channel bandwidth)from the spectrum authority. The GRS transmits a response that verifiesthe channel assignment to the spectrum authority.

In operation S402, a GRS2 registers information of the GRS2 to thespectrum authority and receives assignment of an uplink frequency.

Based on the information, the GCS or the spectrum authority may selectavailable candidate GRSs, may select an appropriate GRS from among thecandidate GRSs through an interference analysis, and may select anuplink time slot and a downlink frequency available in the GRS accordingto distributed and centralized channel assignment methods.

Hereinafter, the distributed and centralized channel assignment methodin which the spectrum authority efficiently assigns and manages alimited spectrum for controlling an unmanned aircraft in the nationalairspace to support the proposed channel assignment method and procedurewill be described.

The proposed unmanned aircraft CNPC dynamic channel assignment methodmay be divided into a distributed channel assignment method and acentralized channel assignment method based on an entity that analyzes aCNPC channel available within the unmanned aircraft CNPC operation rangeof the national airspace into consideration of the unmanned aircraftflight plan and CNPC operation environment at each GCS, and the like.

The distributed and centralized channel assignment methods of the P2Ptype will be described with reference to FIGS. 5A and 5B.

FIG. 5A illustrates an example of a distributed channel assignmentprocedure in a P2P type according to example embodiments.

FIG. 5B illustrates an example of a centralized channel assignmentprocedure in a P2P type according to example embodiments.

In the distributed channel assignment method of the P2P type, a GCSanalyzes an available channel by considering the flight plan and theCNPC operation environment, etc., based on information provided from aspectrum authority and requests the spectrum authority for a singlechannel from the analyzed available channel set, and the spectrumauthority verifies whether the channels requested from the respectiveGCSs are safely available in the aerospace volume and determines whetherto approve the requested channels.

In the distributed channel assignment method, the GCS is required toselect a safe frequency channel to be used during an operation of theunmanned aircraft using an optimal channel selection algorithm tool.

That is, the GCS functions to find an available channel and the spectrumauthority functions to verify whether a frequency channel selected atthe GCS may be safely available in a CNPC operation area within theaerospace volume through an interference analysis algorithm.

This method may reduce burden of the spectrum authority since thespectrum authority provides only a web-based tool through which the GCSmay input flight plan information and selection frequency informationthrough the Internet.

Referring to FIG. 5A, in operation S511, the GCS connects to a server ofthe spectrum authority.

In operation S512, the spectrum authority provides the interferenceanalysis algorithm to the GCS to determine an assignment database andchannel assignment in operation S512. In operation S513, the GCSretrieves an available channel

The assignment database may include information about a currentlyassigned unmanned aircraft CNPC channel, for example, information(signal bandwidth, maximum transmission power, receiver sensitivity,etc.) about waveforms of currently assigned CNPC channels,three-dimensional (3D) locations of the GRS and the unmanned aircraft(including GRS and unmanned aircraft mobility information according tothe flight plan), an antenna pattern, etc. Also, the spectrum authorityprovides, to the GCS, the analysis algorithm used to accept and refusechannel assignment.

Here, the interference analysis algorithm may consider a worst situationthat may be considered as interference based on database informationabout all CNPC interference channels in a current CNPC channelassignment situation due to the flight plan of the unmanned aircraft.

The GCS may develop and use a further efficient and optimal channelselection algorithm based on the interference analysis algorithmprovided from the spectrum authority.

Accordingly, the GCS may use an algorithm tool for analyzinginterference and selecting an optimal CNPC channel based on theinterference analysis algorithm provided from the spectrum authority,and the spectrum authority may use an algorithm tool for analyzinginterference to determine whether the channel selected at the GCS isavailable without interference in the current CNPC channel assignmentsituation.

A priority between GCSs to use a CNPC channel is determined based on afirst-come, first-served (FCFS) basis.

In operation S514, the GCS requests the spectrum authority for assigninga channel and provides the flight plane/CNPC characteristic informationto the spectrum authority.

When the GCS requests the spectrum authority for a CNPC channel inoperation S514, the GCS may provide information (bandwidth, maximumtransmission power, receiver sensitivity, etc.) about a CNPC waveformused in association with radio frequency (RF) compatibility, andtransceiver antenna patterns and locations of the unmanned aircraft andall of the GRSs to the spectrum authority.

Here, an antenna location is 3D information that includes a minimumaltitude and a maximum altitude. In the case of the unmanned aircraft,3D information including the flight plan and the altitude according tothe flight plan of the unmanned aircraft may be provided. In the case ofthe GRS, 3D information including the altitude associated with aninstallation location of the GRS may be provided.

If the GRS is a mobile GRS, the GCS may provide movement information ofthe GRS. The antenna pattern may be provided using 3D antenna beampattern information that includes minimum/maximum antenna gaininformation between the GRS and the unmanned aircraft. If a steeringantenna is used, steering antenna information, for example, steeringbeam accuracy, beam antenna gain, etc., of the unmanned aircraft or theGRS during a period of using the CNPC channel may be provided.

The spectrum authority verifies the availability through interferenceanalysis based on the requested channel information and the flight planand CPNC characteristic information in operation S515, and assigns achannel to the GCS in operation S516.

In operation S517, in response to the channel assignment, the GCStransmits a response that verifies the channel assignment to thespectrum authority.

For the stable operation of the unmanned aircraft in the nationalaerospace, the GCS reports to the spectrum authority about the CNPC linkoutrage that causes a situation in which the unmanned aircraft isuncontrollable during at least a predetermined period of time,generally, a few seconds or less, every time the CNPC link outrageoccurs.

Also, to update and enhance an interference analysis algorithm forselecting an optimal channel for the GRS by applying an assignmentalgorithm to an interference situation according to a current CNPCchannel assignment situation in real time, the GCS may provide CNPC linkstate information of the GCS to the spectrum authority.

The CNPC link state information may include, for example, a BER/FER, aSINR, etc. If each numerical value is less than or equal to a referenceBER/FER or SINR, the GCS may regard that the CNPC link outrage hasoccurred and may report to the spectrum authority about the CNPC linkoutrage.

If the channel assignment is impossible, the spectrum authority notifiesthe GRS that the channel assignment is disallowed in operation S518. TheGCS reconnects to the server of the spectrum authority in operationS519, and verifies whether the assignment database and the interferenceanalysis algorithm are updated and receives related information inoperation S520.

In operation S521, the GCS reselects an available channel throughinterference analysis. In operation S522, the GCS requests again thespectrum authority for assigning a channel and, if the flight plan andthe CNPC characteristic information are updated, provides the updatedflight plan and CNPC characteristic information to the spectrumauthority.

In operation S523, the spectrum authority verifies whether the channelis available through interference analysis based on the requestedchannel information and the updated flight plan and CNPC characteristicinformation. In operation S524, the spectrum authority assigns a channelto the GCS.

In operation S525, in response to the channel assignment, the GCStransmits a response that verifies the channel assignment to thespectrum authority.

Hereinafter, the centralized channel assignment method of the P2P typewill be described with reference to FIG. 5B. In the centralized channelassignment method of the P2P type, the spectrum authority analyzes andassigns a channel suitable for each GCS having requested the channelassignment, based on the flight plan and CNPC operation environmentinformation (CNPC waveform information, such as bandwidth, maximumtransmission power, receiver sensitivity, etc., locations and antennapatterns of the GRS/unmanned aircraft, etc.) provided from each GCS.

That is, in the distributed channel assignment method, the GCS performsthe interference analysis and channel selection process. In thecentralized channel assignment method, the spectrum authority performsthe interference analysis and channel selection process.

In the centralized channel assignment method of the P2P type, a prioritybetween GCSs to use a CNPC channel needs to be defined through anappropriate method in order to optimally utilize insufficient CNPCresources.

In the distributed channel assignment method, the priority may bedetermined based on a FCFS basis. However, in this case, it may bedifficult to efficiently use CNPC resources. The centralized channelassignment method needs to consider a further efficient assignmentpriority in order to optimally use a limited CNPC frequency.

Referring to FIG. 5B, the GCS connects to the server of the spectrumauthority in operation S551, and provides the flight plan and CNPCcharacteristic information to the spectrum authority and requests thespectrum authority for a CNPC channel in operation S552. The spectrumauthority selects one of CPNC channels suitable for the GCS throughinterference analysis in operation S553 and assigns the selected CNPCchannel to the GCS in operation S554. The GCS transmits a response thatverifies the channel assignment in operation S555.

If the channel assignment is impossible, the spectrum authority notifiesthe GCS that the channel assignment is disallowed and in this instance,may also notify the GCS of a reason thereof in the case of thecentralized channel assignment method in operation S556, which differsfrom the distributed channel assignment method.

If the spectrum authority notifies the GCS of the reason why channelassignment is difficult, such as saturation of the CNPC channel, adegraded interference situation, an increase in a number of GCSs thathave requested the channel assignment at the same time, and the like,the GCS may update the flight plan and CNPC characteristic information,etc., to be advantageous for the channel assignment based on thenotified information.

In operation S557, the GCS reconnects to the server of the spectrumauthority. In operation S558, the GCS requests again the spectrumauthority for assigning a channel and provides the updated flight planand CNPC characteristic information.

In operation S559, the spectrum authority selects an available channelthrough interference analysis based on the requested channel informationand the updated flight plan and CNPC characteristic information. Inoperation S560, the spectrum authority assigns the channel to the GCS.

In operation S561, in response to the channel assignment, the GCStransmits a response that verifies the channel assignment to thespectrum authority.

Hereinafter, distributed and centralized channel assignment methods of aP2MP type will be described with reference to FIGS. 6A and 6B.

FIG. 6A illustrates an example of a distributed channel assignmentprocedure in a P2MP type according to example embodiments.

FIG. 6B illustrates an example of a centralized channel assignmentprocedure in a P2MP type according to example embodiments.

In the P2MP type, a plurality of GRSs are present and thus, a P2MP GRSregisters in advance information about the corresponding GRS to aspectrum authority and receives assignment of an uplink frequency to beused at the GRS from the spectrum authority.

In operation S611, the GRS connects to a server of the spectrumauthority. In operation S612, the spectrum authority provides, to theGRS, an interference analysis algorithm for determining an assignmentdatabase and whether to assign a channel In operation S613, the GRSretrieves an available channel

Here, the assignment database may include information about a currentlyassigned unmanned aircraft CNPC channel, for example, information(signal bandwidth, maximum transmission power, receiver sensitivity,etc.) about waveforms of currently assigned CNPC channels, 3D locationsof the GRS and the unmanned aircraft (including GRS and unmannedaircraft mobility information according to the flight plan), an antennapattern, etc. Also, the spectrum authority provides, to the GCS, theanalysis algorithm used to accept and refuse channel assignment.

Here, the interference analysis algorithm may consider a worst situationthat may be considered as interference based on database informationabout all CNPC interference channels in a current CNPC channelassignment situation due to the flight plan of the unmanned aircraftflight plan.

The GRS may develop and use a further efficient and optimal channelselection algorithm based on the interference analysis algorithmprovided from the spectrum authority.

Accordingly, the GRS may use an algorithm tool for analyzinginterference and selecting an optimal CNPC channel based on theinterference analysis algorithm provided from the spectrum authority,and the spectrum authority may use an algorithm tool for analyzinginterference to determine whether the channel selected at the GRS isavailable without interference in the current CNPC channel assignmentsituation.

A priority between GRSs to use a CNPC channel is determined based on anFCFS basis.

When the GRS requests the spectrum authority for a CNPC channel inoperation S614, the GRS may provide information (bandwidth, maximumtransmission power, receiver sensitivity, etc.) about a CNPC waveformused in association with RF compatibility, and transceiver antennapatterns and locations of the unmanned aircraft and all of the GRSs tothe spectrum authority.

Here, an antenna location is 3D information that includes a minimumaltitude and a maximum altitude. In the case of the unmanned aircraft,3D information including the flight plan and the altitude according tothe flight plan of the unmanned aircraft may be provided. In the case ofthe GRS, 3D information including the altitude associated with aninstallation location of the GRS may be provided.

If the GRS is a mobile GRS, the GRS may provide movement information ofthe GRS. The antenna pattern may be provided using 3D antenna beampattern information that includes minimum/maximum antenna gaininformation between the GRS and the unmanned aircraft. If a steeringantenna is used, steering antenna information, for example, steeringbeam accuracy, beam antenna gain, etc., of the unmanned aircraft or theGRS during a period of using the CNPC channel may be provided.

In operation S615, the spectrum authority verifies whether the channelis available through interference analysis based on the requestedchannel information and the flight plan and CNPC characteristicinformation. In operation S616, the spectrum authority assigns a channelto the GCS.

In operation S617, in response to the channel assignment, the GCStransmits a response that verifies the channel assignment to thespectrum authority.

In operation S618, the GCS connects to the server of the spectrumauthority. In the case of uplink, the GCS acquires information aboutavailable candidate GRSs together with an existing CNPC channel databaseprovided from the spectrum authority in operation 619, which is similarto the P2P type, and selects an available GRS and a time slot assignablefrom the GRS through interference analysis in operation S620. In thecase of downlink, the GCS receives assignment of a channel in the samemanner as in the P2P type.

In operation S621, the GCS requests the spectrum authority for assigningthe selected channel, notifies the GRS to be used of the channelassignment, and provides the flight plan and CNPC characteristicinformation.

When requesting the spectrum authority for assigning a channel, the GCSneeds to request the spectrum authority to approve a P2MP GRS to beused. When providing CNPC characteristic information, the GCS has noneed to provide GRS related information.

In operation S622, the spectrum authority verifies whether the channelis available through interference analysis based on the requestedchannel information and the flight plan and CNPC characteristicinformation. In operation S623, the spectrum authority assigns thechannel to the GCS.

In operation S624, in response to the channel assignment, the GCStransmits a response that verifies the channel assignment to thespectrum authority.

If the channel assignment is impossible, the spectrum authority notifiesthe GCS that the channel assignment is disallowed in operation S625. Inoperation S626, the GCS reconnects to the server of the spectrumauthority. In operation S627, the GCS receives an assignment database,GRS information, and the interference analysis algorithm.

In operation S628, the GCS reselects an available channel throughinterference analysis based on the received information. In operationS629, the GCS requests again the spectrum authority for assigning achannel and, if the flight plan and the CNPC characteristic informationare updated, provides the updated flight plan and CNPC characteristicinformation to the spectrum authority.

In operation S630, the spectrum authority verifies whether the channelis available through interference analysis based on the requestedchannel information and the updated flight plan and CNPC characteristicinformation. In operation S631, the spectrum authority assigns a channelto the GCS and approves the GRS.

In operation S632, in response to the channel assignment, the GCStransmits a response that verifies the channel assignment to thespectrum authority.

Dissimilar to the channel assignment method of the P2P type, the channelassignment method of the P2MP type further includes a process in whichthe spectrum authority assigns an uplink frequency channel to the GRS.That is, a channel to be assigned to the GRS is an uplink frequencychannel, a channel to be assigned to the GCS is a downlink frequencychannel and a time slot in an uplink frequency assigned to the GRS inuse is assigned.

Here, if the GRS receives a notification indicating that the channelassignment is disallowed from the spectrum authority, the same procedureas a case in which the GCS receives the notification from the spectrumauthority may proceed.

Dissimilar to the channel assignment method of the P2P type, the P2MPGRS needs to be registered in advance before the channel is assigned tothe GCS. Every time registration information is changed, the GRSnotifies the spectrum authority of the change and the spectrum authorityupdates GRS information.

Hereinafter, the centralized channel assignment method of the P2MP typewill be described with reference to FIG. 6B.

In operation S651, the GRS connects to the server of the spectrumauthority. In operation S652, the GRS requests the spectrum authorityfor assigning an uplink frequency channel and provides GRS information.

Registration information may include CNPC waveform information (signalbandwidth, a number of slots, maximum transmission power, receiversensitivity, etc.) associated with the GRS, GRS antenna patterninformation, and GRS transceiver location information. Also, theregistration information may include information regarding a mobile GRSand a steering antenna pattern, if necessary.

The spectrum authority selects an uplink frequency available in the GRSthrough interference analysis in operation S653, and assigns theselected uplink frequency to the GRS in operation S654. In operationS655, the GRS transmits a response that verifies the channel assignment.

In operation S656, the GCS connects to the server of the spectrumauthority. In operation S657, the GCS requests the spectrum authorityfor assigning a channel and notifies the spectrum authority of a GRS tobe used, and provides the flight plan and CNPC characteristicinformation.

In operation S658, the spectrum authority verifies whether the channelis available through interference analysis based on the requestedchannel information and the flight plan and CNPC characteristicinformation. In operation S659, the spectrum authority assigns thechannel to the GCS.

Similar to the P2P type, in the case of uplink, it is possible toperform interference analysis by acquiring an existing assigned CNPCchannel database, information about available candidate GRSs, etc. Inthis manner, it is possible to request the GRS to be used at the GCS anda time slot assignable from the GRS.

In the case of downlink, a channel is assigned in the same manner as inthe P2P type. The GCS needs to notify the spectrum authority of a GRS tobe used when requesting the spectrum authority for a selected channelDissimilar to the P2P type, GRS related information in CNPCcharacteristic information to be used at the GCS is already registeredto the spectrum authority. Thus, there is no need to provide the GRSrelated information. The spectrum authority assigns an uplink time slotand a downlink frequency channel and approves the GRS to be used.

In operation S660, the GCS transmits a response that verifies thechannel assignment to the spectrum authority.

If the channel assignment is impossible, the spectrum authority notifiesthe GCS that the channel assignment is disallowed and in this instance,may also notify the GCS of a reason thereof in the case of thecentralized channel assignment method in operation S661, which differsfrom the distributed channel assignment method.

If the spectrum authority notifies the GCS of the reason why channelassignment is difficult, such as saturation of the CNPC channel, adegraded interference situation, an increase in a number of GCSs thathave requested the channel assignment at the same time, and the like,the GCS may update the flight plan and CNPC characteristic information,etc., to be advantageous for the channel assignment based on thenotified information.

In operation S662, the GCS reconnects to the server of the spectrumauthority. In operation S663, the GCS requests again the spectrumauthority for assigning a channel and provides the updated flight planand CNPC characteristic information.

In operation S664, the spectrum authority selects an available channelthrough interference analysis based on the requested channel informationand the updated flight plan and CNPC characteristic information. Inoperation S665, the spectrum authority assigns the channel to the GCS.

In operation S666, in response to the channel assignment, the GCStransmits a response that verifies the channel assignment to thespectrum authority.

Dissimilar to the channel assignment method of the P2P type, the channelassignment method of the P2MP type further includes a process in whichthe spectrum authority assigns an uplink frequency channel to the GRS.That is, a channel to be assigned to the GRS is an uplink frequencychannel, a channel to be assigned to the GCS is a downlink frequencychannel and a time slot in an uplink frequency assigned to the GRS inuse is assigned.

Also, the P2MP GRS needs to be registered to the spectrum authoritybefore the channel is assigned to the GCS. Every time registrationinformation is changed, the GRS notifies the spectrum authority of thechange and the spectrum authority needs to update GRS information.

When assigning a channel to the GCS, the spectrum authority also needsto designate the P2MP GRS to be used and the GCS has no need to provideGRS related information when providing CNPC characteristic information.In the P2MP type of FIGS. 6A and 6B, channel assignment and change maybe performed at the GRS based on a centralized type and at the GCS basedon a distributed type, or may be performed at the GRS based on thedistributed type and at the GCS based on the centralized type.

Dissimilar to the P2P type, in the case of the P2MP type, a new networkmay be present. Thus, a different assignment method may be additionallyemployed based on a role of a control station, a network, and thespectrum authority.

For example, a channel assignment method in which the spectrum authoritystatically assigns a bandwidth to the GRS and the GRS functions as thespectrum authority may be applied. If the bandwidth is staticallyassigned to the GRS in a situation in which uplink/downlink frequencybandwidths are asymmetric, the above channel assignment method mayinefficiently use a CNPC spectrum in the entire national airspacevolume.

As another example, a channel assignment method in which the GRSdirectly requests the spectrum authority for a CNPC channel based onrequirements of GCSs for the GRS may be applied. If the GRS requests achannel, the spectrum authority may have difficulty in stably operatingthe unmanned aircraft in the nation airspace volume and a CNPC channelused at each GCS.

FIG. 7 is a block diagram illustrating a computing system to execute adynamic channel assignment and change method and procedure forcontrolling an unmanned aircraft according to example embodiments.

Referring to FIG. 7, a computing system 1000 may include at least oneprocessor 1100, a memory 1300, a user interface input device 1400, auser interface output device 1500, a storage 1600, and a networkinterface 1700 that are connected through a system bus 1200.

The processor 1100 may be a semiconductor device configured to processinstructions stored in a central processing unit (CPU) or the memory1300 and/or the storage 1600. The memory 1300 and the storage 1600 mayinclude various types of volatile or nonvolatile storage media. Forexample, the memory 1300 may include read only memory (ROM) 1310 andrandom access memory (RAM) 1320.

The methods and the operations of the algorithms according to theexample embodiments may be configured through a hardware module, asoftware module, and/or a combination thereof by way of the processor1100. The software module may be provided to storage media, for example,the memory 1300 and/or the storage, 1600. Examples of the storage mediamay include a RAM memory, a flash memory, a ROM memory, an erasableprogrammable ROM (EPROM) memory, an electrically erasable programmableROM (EEPROM) memory, a register, a hard disk, a detachable disk, CD-ROM,etc. The storage media may be coupled with the processor 1100, and theprocessor 1100 may read information from the storage media and writeinformation in the storage media. As another example, the storage mediaand the processor 1100 may be provided in an integral type. Theprocessor 1100 and the storage media may be present in an applicationspecific integrated circuit (ASIC). The ASIC may be present in a userterminal. Also, the processor 1100 and the storage media may be presentas individual components within the user terminal.

The components described in the exemplary embodiments of the presentinvention may be achieved by hardware components including at least oneDSP (Digital Signal Processor), a processor, a controller, an ASIC(Application Specific Integrated Circuit), a programmable logic elementsuch as an FPGA (Field Programmable Gate Array), other electronicdevices, and combinations thereof. At least some of the functions or theprocesses described in the exemplary embodiments of the presentinvention may be achieved by software, and the software may be recordedon a recording medium. The components, the functions, and the processesdescribed in the exemplary embodiments of the present invention may beachieved by a combination of hardware and software.

The processing device described herein may be implemented using hardwarecomponents, software components, and/or a combination thereof. Forexample, the processing device and the component described herein may beimplemented using one or more general-purpose or special purposecomputers, such as, for example, a processor, a controller and anarithmetic logic unit (ALU), a digital signal processor, amicrocomputer, a field programmable gate array (FPGA), a programmablelogic unit (PLU), a microprocessor, or any other device capable ofresponding to and executing instructions in a defined manner. Theprocessing device may run an operating system (OS) and one or moresoftware applications that run on the OS. The processing device also mayaccess, store, manipulate, process, and create data in response toexecution of the software. For purpose of simplicity, the description ofa processing device is used as singular; however, one skilled in the artwill be appreciated that a processing device may include multipleprocessing elements and/or multiple types of processing elements. Forexample, a processing device may include multiple processors or aprocessor and a controller. In addition, different processingconfigurations are possible, such as parallel processors.

The methods according to the above-described example embodiments may berecorded in non-transitory computer-readable media including programinstructions to implement various operations of the above-describedexample embodiments. The media may also include, alone or in combinationwith the program instructions, data files, data structures, and thelike. The program instructions recorded on the media may be thosespecially designed and constructed for the purposes of exampleembodiments, or they may be of the kind well-known and available tothose having skill in the computer software arts. Examples ofnon-transitory computer-readable media include magnetic media such ashard disks, floppy disks, and magnetic tape; optical media such asCD-ROM discs, DVDs, and/or Blue-ray discs; magneto-optical media such asoptical discs; and hardware devices that are specially configured tostore and perform program instructions, such as read-only memory (ROM),random access memory (RAM), flash memory (e.g., USB flash drives, memorycards, memory sticks, etc.), and the like. Examples of programinstructions include both machine code, such as produced by a compiler,and files containing higher level code that may be executed by thecomputer using an interpreter. The above-described devices may beconfigured to act as one or more software modules in order to performthe operations of the above-described example embodiments, or viceversa.

A number of example embodiments have been described above. Nevertheless,it should be understood that various modifications may be made to theseexample embodiments. For example, suitable results may be achieved ifthe described techniques are performed in a different order and/or ifcomponents in a described system, architecture, device, or circuit arecombined in a different manner and/or replaced or supplemented by othercomponents or their equivalents. Accordingly, other implementations arewithin the scope of the following claims.

What is claimed is:
 1. A dynamic channel assignment method of apoint-to-point (P2P) unmanned aircraft system (UAS) comprising aspectrum authority, a ground control station (GCS), a ground radiostation (GRS), and an unmanned aircraft, the method comprising:receiving, at the GCS, assignment of a first communication channel setfor communication between the GCS and the unmanned aircraft from thespectrum authority before takeoff of the unmanned aircraft; receiving,at the GCS, assignment of a second communication channel set before theunmanned aircraft enters a second area when the unmanned aircraft is tomove from a first area in which the first communication channel set isavailable to the second area in which the second communication channelset different from the first communication channel set is available dueto a flight plan of the unmanned aircraft after takeoff of the unmannedaircraft; performing, at the GCS, communication with the unmannedaircraft using the second communication channel set when the unmannedaircraft enters the second area; and maintaining, at the GCS, the firstcommunication channel set when the unmanned aircraft reenters the firstarea from the second area due to the flight plan of the unmannedaircraft, and returning, at the GCS, the first communication channel setto the spectrum authority when the unmanned aircraft does not reenterthe first area due to the flight plan of the unmanned aircraft.
 2. Themethod of claim 1, further comprising: returning, at the GCS, the firstcommunication channel set to the spectrum authority and receivingassignment of a third communication channel set available in a thirdarea from the spectrum authority when the unmanned aircraft enters thethird area due to the flight plan of the unmanned aircraft.
 3. Themethod of claim 1, further comprising: monitoring, at the GCS, a linkstate of a communication channel set in use; and changing, at the GCS,the communication channel set by returning the communication channel setin use to the spectrum authority and by receiving assignment of a newcommunication channel set when the link state of the communicationchannel set in use does not satisfy a reference value.
 4. The method ofclaim 3, wherein the communication channel set includes a primarychannel and a backup channel, and the primary channel and the backupchannel are selected from different frequency bands, respectively. 5.The method of claim 4, wherein the changing of the communication channelset comprises initially changing one of the primary channel and thebackup channel included in the communication channel set andsubsequently changing a remaining one thereof.
 6. The method of claim 1,further comprising: providing, at the GCS, information of acommunication channel set assigned from the spectrum authority to theGRS; and verifying, at the GRS, whether the communication channel set isassigned from the spectrum authority, based on information of thecommunication channel set.
 7. The method of claim 6, wherein thespectrum authority further provides information indicating that thecommunication channel set is assigned from the spectrum authority whenassigning the communication channel set to the GCS, information of thecommunication channel set provided from the GCS to the GRS includesinformation indicating that the communication channel set is assignedfrom the spectrum authority, and the GRS verifies whether thecommunication channel set is assigned from the spectrum authority basedon information indicating that the communication channel set is assignedfrom the spectrum authority.
 8. A dynamic channel assignment method of apoint-to-multipoint (P2MP) unmanned aircraft system (UAS) comprising aspectrum authority, a ground control station (GCS), a ground radiostation (GRS) supporting a plurality of unmanned aircrafts, and anunmanned aircraft, the method comprising: transmitting, at the GRS,information of the GRS to the spectrum authority, and receivingassignment of an uplink frequency set from the spectrum authority;registering, at the spectrum authority, the uplink frequency set andinformation of the GRS to a database of the spectrum authority;receiving, at the GCS, assignment of a first communication channel setfor communication between the GCS and the unmanned aircraft from thespectrum authority before takeoff of the unmanned aircraft; receiving,at the GCS, assignment of a second communication channel set before theunmanned aircraft enters a second area when the unmanned aircraft is tomove from a first area in which the first communication channel set isavailable to the second area in which the second communication channelset different from the first communication channel set is available dueto a flight plan of the unmanned aircraft after takeoff of the unmannedaircraft; performing, at the GCS, communication with the unmannedaircraft using the second communication channel set when the unmannedaircraft enters the second area; and maintaining, at the GCS, the firstcommunication channel set when the unmanned aircraft reenters the firstarea from the second area due to the flight plan of the unmannedaircraft, and returning, at the GCS, the first communication channel setto the spectrum authority when the unmanned aircraft does not reenterthe first area due to the flight plan of the unmanned aircraft.
 9. Themethod of claim 8, further comprising: returning, at the GCS, the firstcommunication channel set to the spectrum authority and receivingassignment of a third communication channel set available in a thirdarea from the spectrum authority when the unmanned aircraft enters thethird area due to the flight plan of the unmanned aircraft.
 10. Themethod of claim 8, further comprising: monitoring, at the GCS, a linkstate of a communication channel set in use; and changing, at the GCS,the communication channel set by returning the communication channel setin use to the spectrum authority and by receiving assignment of a newcommunication channel set when the link state of the communicationchannel set in use does not satisfy a reference value.
 11. The method ofclaim 10, wherein the receiving the assignment of the communicationchannel set comprises receiving an approval of a GRS used at the GCSfrom the spectrum authority, and receiving assignment of a time slot inan uplink frequency assigned to the GRS and a downlink frequency as thecommunication channel set, and the changing of the communication channelset comprises changing, at the GCS, the downlink frequency of thecommunication channel set and the time slot of the uplink frequency. 12.The method of claim 10, wherein the communication channel set includes aprimary channel and a backup channel, and the primary channel and thebackup channel are selected from different frequency bands,respectively.
 13. The method of claim 12, wherein the changing of thecommunication channel set comprises initially changing one of theprimary channel and the backup channel included in the communicationchannel set and subsequently changing a remaining one thereof.
 14. Themethod of claim 8, further comprising: providing, at the GCS,information of a communication channel set assigned from the spectrumauthority to the GRS; and verifying, at the GRS, whether thecommunication channel set is assigned from the spectrum authority, basedon information of the communication channel set.
 15. The method of claim14, wherein the spectrum authority further provides informationindicating that the communication channel set is assigned from thespectrum authority when assigning the communication channel set to theGCS, information of the communication channel set provided from the GCSto the GRS includes information indicating that the communicationchannel set is assigned from the spectrum authority, and the GRSverifies whether the communication channel set is assigned from thespectrum authority based on information indicating that thecommunication channel set is assigned from the spectrum authority.
 16. Adistributed channel assignment method of a point-to-point (P2P) unmannedaircraft system (UAS) comprising a spectrum authority, a ground controlstation (GCS), a ground radio station (GRS) supporting a plurality ofunmanned aircrafts, and an unmanned aircraft, the method comprising:selecting, at the GCS, available channels for communication with theunmanned aircraft based on information provided from the spectrumauthority; requesting, at the GCS, the spectrum authority for assigninga single channel among the available channels; verifying, at thespectrum authority, whether the requested channel is available in aflight area of the unmanned aircraft, and determining whether to approvethe requested channel; and assigning, at the spectrum authority, therequested channel to the GCS when the requested channel is determined tobe approved.
 17. The method of claim 16, further comprising: providing,at the spectrum authority, an assignment database and an interferenceanalysis algorithm for determining whether to assign the channel to theGCS, prior to selecting at the GCS, the available channels, wherein theselecting comprises analyzing, at the GCS, performing interferenceanalysis between frequency channels using the interference analysisalgorithm and selecting a communication channel compatible with anexisting communication channel present in a current flight area of theunmanned aircraft during flight of the unmanned aircraft.
 18. The methodof claim 16, wherein the requesting comprises providing, at the GCS, atleast one of communication link waveform information including abandwidth of the requested channel, a maximum transmission power, and areceiver sensitivity, a GRS to be used at the GCS, and a transceiverlocation and an antenna pattern of the unmanned aircraft.
 19. The methodof claim 16, further comprising: providing, at the GCS, communicationchannel link state information between the GCS and the unmanned aircraftto the spectrum authority; and updating, at the spectrum authority, theinterference analysis algorithm based on the communication channel linkstate information.
 20. The method of claim 19, further comprising:notifying, at the spectrum authority, the GCS that the channelassignment is disallowed if the channel assignment is impossible;receiving, at the GCS, the updated interference analysis algorithm fromthe spectrum authority, reselecting an available channel using theupdated interference analysis algorithm, and requesting again thespectrum authority for the reselected available channel; and assigning,at the spectrum authority, the channel to the GCS when the requestedchannel is determined to be approved.